Meaning
Path of distortion power levels follows a specific mathematical relationship as the input power of two or more signals increases. This third order intermodulation trajectory typically shows a three-to-one slope on a logarithmic scale where every 1 dB increase in input power results in a 3 dB increase in the distortion product. The behavior identifies the point where the distortion would theoretically equal the fundamental signal level.
Understanding this trend is essential for predicting interference in multi-channel communication systems.
Theoretical Intercept
Theoretical intersection of the fundamental and distortion lines defines the linearity of the system. This value is a standard metric for comparing components.
Power Variation
Real-world devices often deviate from the ideal slope as they approach the compression point or as thermal effects change the nonlinear behavior. This third order intermodulation trajectory may shift or flatten when the device enters saturation. Engineers use this information to define the dynamic range where a receiver can operate without being blinded by its own distortion.
Tracking the trajectory across different frequencies reveals the bandwidth limitations of the matching networks. If the slope deviates measurably from the expected three-to-one ratio, it indicates multiple distortion mechanisms are active simultaneously. Test equipment must provide sufficient dynamic range to capture the distortion products before they disappear into the noise floor.
Control Strategy
Control of these signals prevents interference with adjacent channels in the radio spectrum. Mobile devices must maintain their distortion products below a specific threshold defined by regulatory bodies. Proper filtering and power management ensure that the device remains compliant across all operating modes.
